Synthesis and Performance Evaluation of Date Pit Based Surfactant-Polymer Formulation

for Enhanced Chemical Flooding

Jimoh K. Adewole and Abdullah S. Sultan

Center for Petroleum & Minerals, King Fahd University of Petroleum & Minerals,

Dhahran 31261, Saudi Arabia

Outlines

• Introduction• Date Pit Polymers

• Objective

• Experimental Procedure

• Results and Discussion

• Conclusion

• Challenges and Future Works

• Acknowledgement

•an established method employed to prolong the life of an oil well and obtain the maximum recoverable amount of oil from a reservoir •Oil recovery methods are generally subdivided into three stages - primary, secondary and tertiary recovery•About two-third of OOIP is left in the ground after exhausting primary and secondary recovery techniques•This large amount of oil can be recovered using EOR techniques.

Enhanced Oil Recovery (EOR)

Classes of EOR Methods• Thermal (tEOR)

• Chemical (cEOR)

• Gas (gEOR)

Chemical EOR Methods (cEOR)

Individual Injection:

Alkaline

Surfactant

Polymer

Combine Injection:

Surfactant-Polymer (SP) flooding

Alkaline-Surfactant Flooding

Alkaline-Surfactant – Polymer Flooding (ASP)

Major Challenges of cEOR

Cost effectiveness

Cost sensitivity of surfactants and polymers to oil prices

Date Pit Polymers

Saudi Arabia was ranked among the top ten date producing countries in the world

4th largest producer in 2001 (13.3% of global production)

3rd largest producer in 2007

Huge by product from date processing?

Date Pit Polymers Cont’d

500550600650700750800850900950

1990 1995 2000 2005 2010Prod

uctio

n (t

hous

ands

tonn

es)

Year

Fig. 1 Date Production in the Kingdom of Saudi Arabia between 1990 and 2007 (Botes and Zaid, 2002)

Date Pit Polymers Cont’d

Fig. 2 Molecular Structure of Cellulose

Fig. 3 Molecular Structure of Lignin

Fig. 4 Molecular Structure of Hemicellulose

Objective

Investigate the potential of locally available non-petrochemical raw materials for applications in EOR

Specifically, this research work explores the use of local date pits in formulating a surfactant polymer system

Fatty oils from date pit for surfactant (more expensive than the already existing surfactants due to its % composition)

Successful production of polymer from date can facilitate the synthesis of carbohydrate based surfactants which is another area of focus in this project

Oil Content in Seeds

Table 1. Oil Content of Various Types of Seeds Seeds Oil Content (wt%) Africa crabwood 48.00 – 61.5

Castor 35.55

Coconut 64.00

Cotton 15.25

Date pit 5.02 - 12.67

Groundnut 38.50

Jatropha 37.51-35.55

Linseed 35.44

Melon 39.91

Neem 42.45-51.60

Niger 38.50

Palm kernel nut 46.57

Rape/mustard 40.45

Sesame 35.50

Shear nut 34.44

Sunflower 25.40

Average Composition of Date Seeds

Table 2. Average Composition of Date Seeds

Components Contents (%) Moisture 10.20

Ash 1.18

Carbohydrate 72.59 - 86.89,

Crude Proteins 5.67

Fat Contents 5.02 - 12.67

Crude Fiber Content of Date Pit

Table 3 Chemical Composition of Date Pit Fibreous Fraction

Component Molecular Formula Composition (Wt%)

Hemicellulose (C5H8O4)n and (C6H10O5)n 23.3 - 55.5

Lignin C9H10O2, C10H12O3, C11H14O4 14.7 - 23.2

Cellulose C6H10O5 20.18 – 56.7

Ash - 1.1 – 5.3

Experimental Material

Date pit collected from Al Hassa, Saudi Arabia.

Alfoterra ® 123-8S 90 from Sasol, North America Inc

NaOH (Merck)

Distilled water

Experimental Procedure

Date Pit Processing

Soaking of date pits in water

Washing by sonication

Sun drying for 10 days between 38 to 45.5oC

Grinding to powder

De-oiling using hexane in a Soxhlet apparatus

Synthesis of Date Pit Polymer

Mixed solution of NaOH in H2O

Immersion of the de-oiled powder in alkaline solution

Agitation with a Multi-Wrist shaker

Preparation of surfactant-polymer formulation

•date pit polymer mixed with 2wt% Alfoterra

Solubility Test and Calculation

Filtration and and washing with distilled water

Isolation of undissolved fractions

Drying in vacuum oven at 85oC and for about three days

Solubility calculation

1

1max 4.29 WW

WWC

o

o

oW is the initial weight in g and 1W is the weight of undissoled date pit

Solubility Test and Calculation Cont’d

Yield calculation

oo M

M1

oM is the mass of the initial dry date pits

M is the mass of the residue obtained after the reaction.

Viscosity measurement

Measurement was done using Contraves Low-Shear 30 viscometer

Brookfield EX-200 temperature control system

Thermal equilibrium was ensured

Aging also performed

Results and Discussion

Effect of Date Pit Concentration on solubility

0.0

1.0

2.0

3.0

4.0

0.0 1.0 2.0 3.0 4.0Sat

ura

ted S

olu

bil

ity (w

t%)

Weight of Date Pit Powder in Alkaline Solution (g)

Fig. 1 Solubility as a function of Date Pit

maximum value at ~2gcarbohydrate fractioncellulose is dispersionNaOH- hydrates (NaOH.nH2O) formation

Fig. 5 Solubility as a function of Date Pit

Effect of Date Pit Concentration on solubility Cont’d

01020304050607080

0.0 1.0 2.0 3.0 4.0

Yie

ld (%

)

Weight of Date Pit Powder (g)

Fig. 1 Changes in yield with date pit powder reacted with NaOH solution

Yield is between 70 and 57% for date pit weight up to ~2g

Fig. 6 Changes in yield with date pit powder reacted with NaOH solution

Effect of the presence of other componentsHemicellulose interaction with cellulose through hydrogen and covalent bonds (Wang, 2008)Its strong tendency to be deposited on the surface of cellulose fibers reduces it accessibility to the solvents

Viscosity Enhancement Capability

Fig. 7 Viscosity as a function of Concentration of date pit powder at 38oC

Viscosity increment from 0.95cp (for the 2wt% surfactant solution) to about 6cp by addition of 25.76wt% of DPP sampleContinuous increase due to absence of chemical interaction

0

5

10

15

20

25

0.0 2.0 4.0 6.0 8.0 10.0

Visc

osity

(cp)

Weight % Date Pit Powder

Viscosity Enhancement Capability

Fig. 8 Viscosity of surfactant-polymer formulation as a function of DPP concentration, in 2wt% Alfoterra 123-8S-90 at 38oC

The broken line added to predict the viscosity behaviour beyond the experimental values

0123456789

10

0 10 20 30 40

Vis

cosi

ty (cp

)

Concentration of DPP Solution (wt%)

Effect of Temperature of Date Pit Polymer Solution

Fig. 9 Change in Date Pit Polymer Solution Viscosity with Temperature (without Sealing the Surface with Mineral Oil)

incredible pseudo increment in viscosity with increase in temperature

2.02.53.03.54.04.55.0

35.0 45.0 55.0 65.0

Vis

cosi

ty (c

p)

Temperature (oC)

Effect of Temperature of Date Pit Polymer Solution

Fig. 10 Change in Date Pit Polymer Solution Viscosity with Temperature (After Sealing the Surface with Mineral Oil)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

30.0 50.0 70.0 90.0 110.0 130.0

Vis

cosi

ty (c

p)

Temperature (oC)

Day 1

Day 2

Investigation into the effect of temperature on the viscosity with sample covered at the surface using minerals oil.Attempt to test measurement repeatability (Day 1 and Day 2)

Effect of Temperature of Date Pit Polymer Solution

Fig. 11 Viscosity of the DPP solution and aging

Effect of aging time on viscosity at 80oCCovering with oil can only be sustained for more than three daysDue to evaporation of both the mineral oil and the DPP solvent

0.0

0.5

1.0

1.5

2.0

2.5

Day 1 Day 2 Day 3 Day 4 Morning

Day 4 Noon

Day 5

Vis

cosi

ty (c

p)

Time (days)

Conclusion

• Date pit powder can be formulated into a polymer with a potential viscosifying power that can be employed in EOR processes

• Maximum yield of 69% was obtained with NaOH solution which limits the viscosifying power to ~22cp

• The synthesized DPP solution may be applied only to recovery of light crude with viscosity lower than 22cp

• It can also be used as blend with other high viscosity polymer to improve their performance

Challenges and Future Works

non availability of better solvent for higher solubility of date pit powder

Challenges

Future Works

• Investigation of other chemical modification routes to obtain date pit polymer with higher viscosity

• synthesis of carbohydrate based surfactant from date • study of the synergy between date pit polymer and carbohydrate

based surfactant and surfactant from other seeds

Acknowledgement

Center for Petroleum & Minerals, KFUPM

Mr Sulaiman H. Al-Hulaili

Mr Ahmad Adewunmi

Mr Abdulrahim Muhammadain

Mr. Abdulsamad Iddrisu

Thank you